The present invention relates to a boundary scan element for use in a boundary scan test method and a communication system in which the element is applied to and used as a communication element, and more particularly to a boundary scan element that enables high-speed transfer of data and a communication system using the element.
A boundary scan test method has been proposed as one of the inspection methods by which it is tested, with a plurality of IC chips being disposed on a printed wire board with printed wires formed thereon, whether or not the respective IC chips are connected to the respective printed wires correctly and whether or not there is any break in the respective printed wires, etc.
This boundary scan test method can be applied to integrated circuits (IC chips) into which boundary scan elements are incorporated. For example, as shown in FIG. 5, the boundary scan element comprises a plurality of boundary cells 214 disposed individually between input/output terminals of an internal logic circuit 211 for implementing the inherent functions of an integrated circuit 210, and input/output terminals 212/213 of the integrated circuit 210, a TAP controller (TAP circuit) 219 for controlling input and output of data to the boundary cells 214, a TDI terminal 220 for receiving test data, a TDO terminal 221 for transmitting test data, a TCK terminal 222 to which a clock signal is input, and a TMS terminal 223 for receiving a mode signal for switching the operation mode of the TAP controller 219. In addition, as required, the boundary scan element is provided with a bypass register 215, and an ID CODE register 216, an instruction register 217, or a TRS terminal 224 for receiving a reset signal. Incidentally, the bypass register 215xe2x80x94the instruction register 217 are designated as a boundary scan register (218).
Explaining the respective terminals and the signals to be input and output at the respective terminals in detail, TDI (Test Data In) is a signal for serial input of commands or data to a test logic, being sampled on the rising edge of TCK. TDO (Test Data Out) is a signal for serial output of data from the test logic, and an output value is changed on the falling edge of TCK. TCK (Test Clock) supplies a clock to the test logic, and is a dedicated input that allows a serial test data path to be used independent of the system clock inherent to the component. TMS (Test Mode Select) is a signal for controlling test operations, being sampled on the rising edge of TCK. The TAP controller decodes this signal. TRST (Test Reset) is a negative logic symbol for initializing the TAP controller in an asynchronous manner and is optional.
The integrated circuit 210 into which such boundary scan elements are incorporated can be tested on the operation conditions thereof and the connections between the integrated circuit 210 and external devices thereof in accordance with the procedures to be mentioned below.
First, to check for a quality of the internal logic 211 of the integrated circuit 210, serial data (test data) is shifted and set to the respective boundary cells 214 corresponding to the respective input terminals 212 while being input to the TDI terminal 220 of the integrated circuit 210. After the integrated circuit 210 is activated under this condition, the data having been set to the respective boundary cells 214 corresponding to the respective output terminals 213 is shifted to be output from the TDO terminal 221. In accordance with the relationship between the resultant serial data (test result data) and the test data input to the integrated circuit 210, it is tested whether or. not the internal logic 211 of the integrated circuit 210 is good.
Furthermore, the boundary scan test method can be applied to a plurality of integrated circuits if boundary scan elements are incorporated therein.
For example, for a plurality of integrated circuits 210 mounted on the board 226 as shown in FIG. 6, the integrated circuits 210 can be tested on themselves in conjunction with a test on a break in printed patterns between the integrated circuits 210.
In this case, the respective boundary scan elements incorporated into the plurality of integrated circuits 210 are connected in series. Specifically, the TDO terminal 221 of a first integrated circuit 210 (on the left in the figure) is connected to the TDI terminal 220 of a second integrated circuit 210 (on the right in the figure). Furthermore, the output terminal 229 of the boundary scan controller board 228 provided in the host computer unit 227 or the like is connected to the TDI terminal 220 of the first integrated circuit 210. Still furthermore, the input terminal 230 of the boundary scan controller board 228 is connected to the TDO terminal 221 of the second integrated circuit 210. The test procedure is as follows.
In the case of testing a break, short-circuit, or the like in printed patterns, test data (serial data) is prepared using a test data preparing tool 231 or the like, and then output from the output terminal 229 of the boundary scan controller board 228. Then, while being input to the TDI terminal 220 of the first integrated circuit 210, the data is shifted and set to the respective boundary cells 214 corresponding to the respective output terminals 213 of the integrated circuit 210. Under this condition, the data stored in these respective boundary cells 214 is output from the respective output terminals 213 provided on the first integrated circuit 210 as shown in FIG. 7. Additionally, the data is input to the respective input terminals 212 of the second integrated circuit 210 via respective printed patterns 233 constituting a system bus or the like, and furthermore captured by the respective boundary cells 214 corresponding to these respective input terminals 212.
Thereafter, the data stored in the respective boundary cells 214 of these respective integrated circuits 210 is shifted, and analyzed using the test result analysis tool 232 while being captured by the input terminal 230 of the boundary scan controller board 228. This allows a test on the break, short-circuit and the like within the test range 235 of the printed pattern 233 that connects between the integrated circuits 210.
Now, in the case of testing the internal logic 211 of the respective integrated circuits 210, test data is output from the output terminal 229 of the boundary scan controller board 228. Then, while being input to the TDI terminal 220 of the first integrated circuit 210, the data is shifted and set to the respective boundary cells 214 corresponding to the respective input terminals 212 of the integrated circuit 210 as shown in FIG. 8.
Subsequently, the integrated circuit 210 is activated and the respective boundary cells 214 corresponding to the respective output terminals 213 are allowed to capture the resultant data. Thereafter, the data stored in these respective boundary cells 214 is shifted and output from the TDO terminal 221 of the first integrated circuit 210. At this time, the boundary scan controller board 228 drives the second integrated circuit 210 into a bypass state as shown in FIG. 7. This allows the data output from the TDO terminal 221 to bypass the second integrated circuit 210 and to be captured by the input terminal 230 of the boundary scan controller board 228. Additionally, the test analysis tool 232 or the like is used to analyze the captured data, thereby allowing a test on whether or not the first integrated circuit 210 operates properly.
Now, in the case of testing the second integrated circuit 210, in a like manner, the boundary scan controller board 228 drives the first integrated circuit 210 into a bypass state as shown in FIG. 8. Thereafter, test data is output from the output terminal 229 of the boundary scan controller board 228 and is allowed to bypass the first integrated circuit 210. Then, while being input to the TDI terminal 220 of the second integrated circuit 210, the test data is shifted and set to the respective boundary cells 214 corresponding to the respective input terminals 212 of the second integrated circuit 210 as shown in FIG. 9. Subsequently, this integrated circuit 210 is activated, and the respective boundary cells 214 corresponding to the respective output terminals 213 are allowed to capture the resultant data. Thereafter, the data stored in the respective boundary cells 214 is shifted to be output from the TDO terminal 221 and further captured by the input terminal 230 of the boundary scan controller board 228. Then, the test result analysis tool 232 or the like is used to analyze the captured data, thereby allowing a test on whether or not the second integrated circuit 210 operates properly.
As mentioned above, such a board 226 that uses integrated circuits 210 into which boundary scan elements are incorporated can be tested on a quality of the respective integrated circuits 210 themselves and connections between the integrated circuits 210 by applying the boundary scan test method.
Incidentally, when the inventor constructed a sensor module board and the like using integrated circuits into which such boundary scan elements were incorporated, the inventor has discovered that the input and output of serial data can be performed with the respective integrated circuits mounted on the board 226 at a rate on the order of 20 Mbps without using communication integrated circuits.
Then, the inventor has proposed a communication system to which boundary scan elements are applied and which allows for communicating with a host computer or the like without using a communication device.
FIG. 10 is a block diagram showing an example of a communication system to which boundary scan elements are applied.
The communication system 240 shown in the figure includes a communication controller unit 241 for transmitting and collecting communication data, and the like, a plurality of sensor units 242a-242c for monitoring a target object to be monitored, and the like, a plurality of boundary scan elements 243a-243c being disposed for the respective sensor units 242a-242c and performing such processing as capturing the control data output from the communication controller 241 and then supplying the data to the respective sensor units 242a-242c, and as capturing detection data or the like to be output from these respective sensor units 242a-242c and then supplying the data to the communication controller 241, and communication lines 244 for connecting these respective boundary scan elements 243a-243c to said communication controller unit 241.
The respective boundary scan elements 243a-243c are connected in series to the communication controller unit 241. Specifically, the output terminal 241a of the communication controller unit 241 is connected to the TDI terminal of the boundary scan element 243a, the TDO terminal of the boundary scan element 243a is connected to the TDI terminal of the subsequent boundary scan element 243b, and so on. The TDO terminal of the boundary scan element 243c is connected to the input terminal 241b of the communication controller unit 241.
The action of the communication system 240 is as follows.
The respective boundary scan elements 243a-243c are allowed to function in synchronization with the clock signal to be transmitted from the TCK terminal 241d of the communication controller unit 241. In addition, the TMS signal to be transmitted from the TMS terminal 241c of the communication controller unit 241 switches the operation mode of the respective TAP controllers.
Then, in the case of driving the respective sensor units 242a-242c in accordance with the instruction from the host computer unit 245, control data (serial data) is output from the output terminal 241a of the communication controller unit 241. Then, the data is supplied to the respective boundary scan elements 243a-243c and set to the boundary cells corresponding to the output terminals. Then, the control data thus set is output from the output terminals and supplied to the respective sensor units 242a-242c corresponding to the respective boundary scan elements 243a-243c to drive them.
Furthermore, in the case of collecting detection data or the like from the respective sensor units 242a-242c in accordance with the direction form the host computer unit 245, the detection data or the like of the respective sensor units 242a-242c is once set to the boundary cells corresponding to the input terminals of the corresponding respective boundary scan elements 243a-243c. Then, the data is output as serial data from the TDO terminal and captured at the input terminal 241b of the communication controller unit 241.
Such communication system 240 allows its data transfer rate to be 20 Mbps at the maximum and thus enables transferring of communication data at a higher transfer rate than by means of a prior-art communication system in the case of setting control data to the respective boundary scan elements 243a-243c or in the case of allowing the respective boundary scan elements 243a-243c to output detection data or the like.
On the other hand, since the prior-art boundary scan element has all boundary cells connected in series between the TDI and TDO terminals even, for example, in the case of setting data only to the boundary cells assigned to the output terminals, the data had to be shifted in sequence from the boundary cells assigned to the input terminals in some cases.
This prevents the time for executing the boundary scan test method from being shortened and high-speed transfer of data in the case of applying boundary scan elements to communication elements as the inventor did.
An object of the present invention is to provide a boundary scan element and a communication system employing the same, which enables high-speed transfer of data to boundary cells.
According to the present invention, there is provided a boundary scan element comprising a plurality of input-terminal-side boundary cells connected in series and assigned individually to respective input terminals, a plurality of output-terminal-side boundary cells connected in series and assigned individually to respective output terminals, a TAP circuit for controlling input and output of data to or from the aforesaid input-terminal-side and output-terminal-side boundary cells, a TDI terminal for inputting serial data to be provided to the aforesaid boundary cells, a TDO terminal for outputting data from the aforesaid boundary cells as serial data, a TCK terminal to which a clock signal is input, and a TMS terminal to which a mode signal is input to switch an operation mode of the aforesaid TAP circuit, wherein the aforesaid input-terminal-side boundary cells and the aforesaid output-terminal-side boundary cells are connected in parallel between the aforesaid TDI terminal and the aforesaid TDO terminal.
In the present invention, all boundary cells are not connected in series as in the prior art, but the input-terminal-side boundary cells assigned to the input terminals and the output-terminal-side boundary cells assigned to the output terminals are connected in parallel between the TDI terminal and the TDO terminal.
Therefore, for example, in the case where data from the TDI terminal is set to the output-terminal-side boundary cells, it is made possible to transfer the data directly to the output-terminal-side boundary cells without passing through the input-terminal-side boundary cells, so that high-speed transfer of test data or the like to boundary cells can be implemented.
Furthermore, the boundary scan element of the present invention can be also configured in such a manner that two of each of the TDI terminal and the TDO terminal are provided, the input-terminal-side boundary cells are connected between either one of the TDI terminals and either one of the TDO terminals, and the output-terminal-side boundary cells are connected between the other one of the TDI terminals and the other one of the TDO terminals.
Such configuration enables simultaneous transfer of data to both the input-terminal-side boundary cells and the output-terminal-side boundary cells, thereby enabling further improvement in high-speed transfer of test data or the like to boundary cells.
In the foregoing, the boundary scan element of the present invention may be either encapsulated in an independent single package itself or incorporated into other IC.
Furthermore, when the boundary scan element is encapsulated in an independent package, the input and output terminals mean the input and output terminals thereof. When it is incorporated into other IC, they mean the input and output terminals of the IC.
Now, according to the present invention, there is provided a communication system comprising boundary scan elements each having a plurality of input-terminal-side boundary cells connected in series and assigned individually to respective input terminals, a plurality of output-terminal-side boundary cells connected in series and assigned individually to respective output terminals, a TAP circuit for controlling input and output of data to or from the aforesaid input-terminal-side and output-terminal-side boundary cells, a TDI terminal for inputting serial data to be provided to the aforesaid boundary cells, a TDO terminal for outputting data from the aforesaid boundary cells as serial data, a TCK terminal to which a clock signal is input, and a TMS terminal to which a mode signal is input to switch an operation mode of the aforesaid TAP circuit; a plurality of terminal devices respectively connected to the aforesaid boundary scan elements or having an IC into which the elements are incorporated; and a communication controller to which the aforesaid boundary scan elements are connected in series and which transmits and receives communication date for controlling the aforesaid terminal devices individually via the aforesaid boundary scan elements, wherein each of the aforesaid boundary scan elements has the aforesaid input-terminal-side boundary cells and the aforesaid output-terminal-side boundary cells connected in parallel between the aforesaid TDI terminal and the aforesaid TDO terminal.
The communication system of the present invention employs the boundary scan elements as communication elements in order to control the terminal devices by means of the communication controller.
That is, in the case of transferring communication data to the terminal devices, the communication data is once transferred from the communication controller to the output-terminal-side boundary cells of the boundary scan elements, and thereafter the communication data is transmitted from the boundary scan elements to the terminal devices. On the other hand, in the case of receiving communication data from the terminal devices, the communication data is once transferred from the terminal devices to the input-terminal-side boundary cells of the boundary scan elements, and thereafter the communication data is transmitted from the boundary scan elements to the communication controller.
In addition, since the boundary scan elements have the input-terminal-side boundary cells and output-terminal-side boundary cells connected in parallel between the TDI terminal and the TDO terminal, communication data can be directly transferred to the respective-terminal-side boundary cells via the TDI terminal and the TDO terminal.
Therefore, communication data can be transferred at a greater transfer rate than by means of a communication system employing prior-art boundary scan elements in which all boundary cells are connected in series.
Furthermore, according to the present invention, there is provided a communication system comprising boundary scan elements each having a plurality of input-terminal-side boundary cells connected in series and assigned individually to respective input terminals, a plurality of output-terminal-side boundary cells connected in series and assigned individually to respective output terminals, a TAP circuit for controlling input and output of data to or from the aforesaid input-terminal-side and output-terminal-side boundary cells, TDI terminals for inputting serial data to be provided to the aforesaid boundary cells, TDO terminals for outputting data from the aforesaid boundary cells as serial data, a TCK terminal to which a clock signal is input, and a TMS terminal to which a mode signal is input to switch an operation mode of the aforesaid TAP circuit; a plurality of terminal devices connected to the aforesaid respective boundary scan elements or having an IC into which the elements are incorporated, and a communication controller to which the aforesaid boundary scan elements are connected in series and which transmits and receives communication date for controlling the aforesaid terminal devices individually via the aforesaid boundary scan elements; wherein the aforesaid TDI terminals and the aforesaid TDO terminal of each of the aforesaid boundary scan elements comprise a first TDI terminal and a first TDO terminal connected respectively to opposite ends of the aforesaid input-terminal-side boundary cells, and a second TDI terminal and a second TDO terminal connected respectively to opposite ends of the aforesaid output-terminal-side boundary cells, that the aforesaid second TDI terminal of either one of the aforesaid boundary scan elements located on both ends is connected with a data output terminal of the aforesaid communication controller and the aforesaid first TDO terminal thereof is connected with a data input terminal of the aforesaid communication controller, and that the aforesaid second TDO terminal and the aforesaid first TDI terminal of the other one of the aforesaid boundary scan elements are connected.
The communication system of the present invention employs, as communication elements, the boundary scan elements mentioned above in order to control the terminal devices by means of the communication controller.
That is, the TDI terminal and the TDO terminal of the boundary scan elements comprise a first TDI terminal and a first TDO terminal connected respectively to opposite ends of the input-terminal-side boundary cells, and a second TDI terminal and a second TDO terminal connected respectively to opposite ends of the output-terminal-side boundary cells; thereby enabling simultaneous transfer of mutually different communication data to the input-terminal-side and output-terminal-side boundary cells, and enabling communication data to be transferred at a still higher transfer rate than by means of the communication system of the present invention mentioned above.
The communication system of the present invention may employ various sensor units, for example, monitoring cameras or the like as the aforesaid terminal devices. In addition, concerning the connection between the terminal devices and the boundary scan elements, the output terminals are connected to the input terminals of the terminal devices and the input terminals are connected to the output terminals of the terminal devices respectively, thereby allowing data of the boundary cells to be output to the terminal devices, and conversely, the data to be input to the boundary cells.
The aforesaid communication data include, in addition to control data transmitted to the terminal devices to control the same, the data detected by the terminal devices transmitted by the aforesaid terminal devices, and status data indicating whether or not the terminal devices are being operated normally, and the like.